The stimulated Brillouin scattering （SBS） threshold enhancement factor in a pure white noise linewidth broad- ening Yb-doped fiber amplifier （YDFA） with a short large mode area fiber is theoretically and experimen...The stimulated Brillouin scattering （SBS） threshold enhancement factor in a pure white noise linewidth broad- ening Yb-doped fiber amplifier （YDFA） with a short large mode area fiber is theoretically and experimentally studied. We demonstrate a 1064.08nm, 11.6 GHz finewidth, 1.5 k W output power YDFA with an SBS threshold enhancement of -57 （26 W SBS threshold with single frequency seed）. The output beam is near-diffraction lim- ited with a beam quality factor elM2 = 1.15 and a slope efficiency of up to 87%. No SBS or stimulated Raman scattering effects are observed in the whole power range. Further power sealing is limited by the available pump power in our system.展开更多
Objective To analyze the factors that impact the environment quality of cleaning operating room and to discuss improvement measurement. Methods Environment bacteria testing results and prevalence of surgical incision ...Objective To analyze the factors that impact the environment quality of cleaning operating room and to discuss improvement measurement. Methods Environment bacteria testing results and prevalence of surgical incision infection in cleaning operating room were retro-展开更多
In the multistage reliability growth tests with instant and delayed fix modes, the failure data can be assumed to follow Weibull processes with different parameters at different stages. For the Weibull process within ...In the multistage reliability growth tests with instant and delayed fix modes, the failure data can be assumed to follow Weibull processes with different parameters at different stages. For the Weibull process within a stage, by the proper selection of prior distribution form and the parameters, a concise posterior distribution form is obtained, thus simplifying the Bayesian analysis. In the multistage tests, the improvement factor is used to convert the posterior of one stage to the prior of the subsequent stage. The conversion criterion is carefully analyzed to determine the distribution parameters of the subsequent stage＇s variable reasonably. Based on the mentioned results, a new synthetic Bayesian evaluation program and algorithm framework is put forward to evaluate the multistage reliability growth tests with instant and delayed fix modes. The example shows the effectiveness and flexibility of this method.展开更多
Quantitative security metrics are desirable for measuring the performance of information security controls. Security metrics help to make functional and business decisions for improving the performance and cost of the...Quantitative security metrics are desirable for measuring the performance of information security controls. Security metrics help to make functional and business decisions for improving the performance and cost of the security controls. However, defining enterprise-level security metrics has already been listed as one of the hard problems in the Info Sec Research Council's hard problems list. Almost all the efforts in defining absolute security metrics for the enterprise security have not been proved fruitful. At the same time, with the maturity of the security industry, there has been a continuous emphasis from the regulatory bodies on establishing measurable security metrics. This paper addresses this need and proposes a relative security metric model that derives three quantitative security metrics named Attack Resiliency Measure(ARM), Performance Improvement Factor(PIF), and Cost/Benefit Measure(CBM) for measuring the performance of the security controls. For the effectiveness evaluation of the proposed security metrics, we took the secure virtual machine(VM) migration protocol as the target of assessment. The virtual-ization technologies are rapidly changing the landscape of the computing world. Devising security metrics for virtualized environment is even more challenging. As secure virtual machine migration is an evolving area and no standard protocol is available specifically for secure VM migration. This paper took the secure virtual machine migration protocol as the target of assessment and applied the proposed relative security metric model for measuring the Attack Resiliency Measure, Performance Improvement Factor, and Cost/Benefit Measure of the secure VM migration protocol.展开更多
Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in re...Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years. In this paper, for this type of regenerator, its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method. The results show that the optimal improvement of signal Q factor can reach more than 2.2 dB.展开更多
In this paper some improvements on certainty factor model are discussed aiming at:1)including, in a rule“E→H”,not only the CF of H when E exists but also CF of(?)when E does not exist(partly or completely).For this...In this paper some improvements on certainty factor model are discussed aiming at:1)including, in a rule“E→H”,not only the CF of H when E exists but also CF of(?)when E does not exist(partly or completely).For this purpose another factor(?)is added into the original model;2) improving the model so that it can tackle problems with unknown evidence.In this aspect two concepts are introduced:(relative)maximum existence risk and(relative)maximum non-existence risk.An impor- tant result is that even if some necessary evidence is unknown one can still know the tendency whether the conclusion is true.Based on the improvements a conflict resolution model for problem-level conflict is also presented展开更多
The aging of machine can be slowed and the life of machine can be increased by implementing periodic predictive maintenance. In this article,an improvement factor considering maintenance cost,age of machine and learni...The aging of machine can be slowed and the life of machine can be increased by implementing periodic predictive maintenance. In this article,an improvement factor considering maintenance cost,age of machine and learning effect in the process of maintaining is constructed to describe the effect of periodic preventive maintenance. The model of improvement factor can be fitted through health index. Based on improvement factor with infinite time,cost function including preventive maintenance cost,minimal repair cost and replacement cost is explored. The unit cost and the optimized maintenance time interval based on limit of reliability are deduced. The process of optimization and an example are given.展开更多
The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair ...The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair rates to be constant.The system availability is defined as the ability of the system to satisfy consumer demand.Factor improvement method and standby redundancy method are used to improve the system design.To evaluate availability of the both original and improved systems,a fast technique,based on universal generating function,is adopted.The availability equivalence factor is introduced to compare different system designs.Two types of availability equivalence factors of the system are derived.A numerical example is provided to illustrate how to utilize the obtained results.展开更多
This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezores...This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezoresistive energy pumping,which was previously demonstrated to drive self-sustained mechanical oscillation,can turn the relatively weak piezoresistivity of silicon into a viable electronic amplification mechanism with power gains of 420 dB.Various functionalities ranging from frequency selection and timing to sensing and actuation have been successfully demonstrated for microscale and nanoscale electromechanical systems.Although such capabilities complement solid-state electronics,enabling state-of-the-art compact and high-performance electronics,the amplification of electronic signals is an area where micro-/nanomechanics has not experienced much progress.In contrast to semiconductor devices,the performance of the proposed nanoelectromechanical amplifier improves significantly as the dimensions are reduced to the nanoscale presenting a potential pathway toward deep-nanoscale electronics.The nanoelectromechanical amplifier can also address the need for ultranarrow-band filtering along with the amplification of lowpower signals in wireless communications and certain sensing applications,which is another need that is not efficiently addressable using semiconductor technology.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos U1330134,61308024 and 11174305the National High-Technology Research and Development Program of China under Grant No 2014AA041901the Shanghai Natural Science Foundation under Grant No 11ZR1441400
文摘The stimulated Brillouin scattering （SBS） threshold enhancement factor in a pure white noise linewidth broad- ening Yb-doped fiber amplifier （YDFA） with a short large mode area fiber is theoretically and experimentally studied. We demonstrate a 1064.08nm, 11.6 GHz finewidth, 1.5 k W output power YDFA with an SBS threshold enhancement of -57 （26 W SBS threshold with single frequency seed）. The output beam is near-diffraction lim- ited with a beam quality factor elM2 = 1.15 and a slope efficiency of up to 87%. No SBS or stimulated Raman scattering effects are observed in the whole power range. Further power sealing is limited by the available pump power in our system.
文摘Objective To analyze the factors that impact the environment quality of cleaning operating room and to discuss improvement measurement. Methods Environment bacteria testing results and prevalence of surgical incision infection in cleaning operating room were retro-
基金supported by Pre-research Foundation of General Armament Department of China(xxxxxxxxxxxx06KG0164)and the National Doctoral Foundation of China (2005999807).
文摘In the multistage reliability growth tests with instant and delayed fix modes, the failure data can be assumed to follow Weibull processes with different parameters at different stages. For the Weibull process within a stage, by the proper selection of prior distribution form and the parameters, a concise posterior distribution form is obtained, thus simplifying the Bayesian analysis. In the multistage tests, the improvement factor is used to convert the posterior of one stage to the prior of the subsequent stage. The conversion criterion is carefully analyzed to determine the distribution parameters of the subsequent stage＇s variable reasonably. Based on the mentioned results, a new synthetic Bayesian evaluation program and algorithm framework is put forward to evaluate the multistage reliability growth tests with instant and delayed fix modes. The example shows the effectiveness and flexibility of this method.
文摘Quantitative security metrics are desirable for measuring the performance of information security controls. Security metrics help to make functional and business decisions for improving the performance and cost of the security controls. However, defining enterprise-level security metrics has already been listed as one of the hard problems in the Info Sec Research Council's hard problems list. Almost all the efforts in defining absolute security metrics for the enterprise security have not been proved fruitful. At the same time, with the maturity of the security industry, there has been a continuous emphasis from the regulatory bodies on establishing measurable security metrics. This paper addresses this need and proposes a relative security metric model that derives three quantitative security metrics named Attack Resiliency Measure(ARM), Performance Improvement Factor(PIF), and Cost/Benefit Measure(CBM) for measuring the performance of the security controls. For the effectiveness evaluation of the proposed security metrics, we took the secure virtual machine(VM) migration protocol as the target of assessment. The virtual-ization technologies are rapidly changing the landscape of the computing world. Devising security metrics for virtualized environment is even more challenging. As secure virtual machine migration is an evolving area and no standard protocol is available specifically for secure VM migration. This paper took the secure virtual machine migration protocol as the target of assessment and applied the proposed relative security metric model for measuring the Attack Resiliency Measure, Performance Improvement Factor, and Cost/Benefit Measure of the secure VM migration protocol.
基金Project supported by the Scientific Fund for Chinese Universities (Grant No. BUPT 2011RC009)
文摘Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years. In this paper, for this type of regenerator, its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method. The results show that the optimal improvement of signal Q factor can reach more than 2.2 dB.
文摘In this paper some improvements on certainty factor model are discussed aiming at:1)including, in a rule“E→H”,not only the CF of H when E exists but also CF of(?)when E does not exist(partly or completely).For this purpose another factor(?)is added into the original model;2) improving the model so that it can tackle problems with unknown evidence.In this aspect two concepts are introduced:(relative)maximum existence risk and(relative)maximum non-existence risk.An impor- tant result is that even if some necessary evidence is unknown one can still know the tendency whether the conclusion is true.Based on the improvements a conflict resolution model for problem-level conflict is also presented
基金the National Natural Science Foundation of China(Nos.50875168 and 50905115)
文摘The aging of machine can be slowed and the life of machine can be increased by implementing periodic predictive maintenance. In this article,an improvement factor considering maintenance cost,age of machine and learning effect in the process of maintaining is constructed to describe the effect of periodic preventive maintenance. The model of improvement factor can be fitted through health index. Based on improvement factor with infinite time,cost function including preventive maintenance cost,minimal repair cost and replacement cost is explored. The unit cost and the optimized maintenance time interval based on limit of reliability are deduced. The process of optimization and an example are given.
基金supported in part by the Natural Science Foundation of Hebei Province under Grant Nos.A2014203096 and G2012203136the National Natural Science Foundation of China under Grant No.11201408the Science Research Project of Yanshan University under Grant No.13LGA017
文摘The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair rates to be constant.The system availability is defined as the ability of the system to satisfy consumer demand.Factor improvement method and standby redundancy method are used to improve the system design.To evaluate availability of the both original and improved systems,a fast technique,based on universal generating function,is adopted.The availability equivalence factor is introduced to compare different system designs.Two types of availability equivalence factors of the system are derived.A numerical example is provided to illustrate how to utilize the obtained results.
基金This work was supported by National Science Foundation CAREER grant No.1056068.
文摘This study demonstrates amplification of electrical signals using a very simple nanomechanical device.It is shown that vibration amplitude amplification using a combination of mechanical resonance and thermal-piezoresistive energy pumping,which was previously demonstrated to drive self-sustained mechanical oscillation,can turn the relatively weak piezoresistivity of silicon into a viable electronic amplification mechanism with power gains of 420 dB.Various functionalities ranging from frequency selection and timing to sensing and actuation have been successfully demonstrated for microscale and nanoscale electromechanical systems.Although such capabilities complement solid-state electronics,enabling state-of-the-art compact and high-performance electronics,the amplification of electronic signals is an area where micro-/nanomechanics has not experienced much progress.In contrast to semiconductor devices,the performance of the proposed nanoelectromechanical amplifier improves significantly as the dimensions are reduced to the nanoscale presenting a potential pathway toward deep-nanoscale electronics.The nanoelectromechanical amplifier can also address the need for ultranarrow-band filtering along with the amplification of lowpower signals in wireless communications and certain sensing applications,which is another need that is not efficiently addressable using semiconductor technology.
